A circuit for filtering a signal corresponding to a time of flight (TOF) of light from a laser reflected off an object to a photo detector, the circuit includes a preamplifier, a DC cancelation loop, and an AC cancelation loop. The preamplifier may be configured to receive the signal from the photo detector corresponding to an output of the laser reflected off an object remote from the laser and photo detector. The DC cancelation loop includes a current feedback DC servo loop. The AC cancelation loop includes a feedback network driven by a floating class AB output stage, and the preamplifier configured to drive the floating class AB output stage, wherein the preamplifier is driven by an error signal of the feedback network and creates an AC signal path with the feedback network and floating class AB output stage.
Legal claims defining the scope of protection, as filed with the USPTO.
2. The circuit of claim 1, wherein the floating class AB output stage includes a dynamically degenerated current mirror.
3. The circuit of claim 1, wherein the feedback network includes switches coupled between an input and output of the floating class AB output stage.
4. The circuit of claim 3, wherein, in response to an absolute value of an output of the floating class AB output stage exceeding twice a threshold voltage of level shift switches of the feedback network, the feedback network is configured to transition from capacitive operation to resistive operation based on a resistive channel of the switches controlled by the level shift switches.
5. That circuit of claim 1, wherein the preamplifier includes a bias voltage regulation loop that sets an input bias voltage for the floating class AB output stage.
6. The circuit of claim 1, wherein the photo detector is an avalanche photo diode.
7. The circuit of claim 6, wherein the error signal is based on an output current of the avalanche photo diode (IAPD) reduced by an output current of the feedback network (IFB,AC).
9. The method of claim 8, wherein the feedback network includes switches coupled between an input and output of the floating class AB output stage.
10. The method of claim 9 further comprising, in response to an absolute value of an output of the floating class AB output stage exceeding twice a threshold voltage of level shift switches of the feedback network, configuring the feedback network to transition from capacitive operation to resistive operation based on a resistive channel of the switches controlled by the level shift switches.
11. That method of claim 8, wherein the preamplifier includes a bias voltage regulation loop that sets an input bias voltage for the floating class AB output stage.
12. The method of claim 8, wherein the floating class AB output stage includes a dynamically degenerated current mirror.
13. The method of claim 8, wherein the photo detector is an avalanche photo diode.
14. The method of claim 13, wherein the error signal is based on an output current of the avalanche photo diode (IAPD) reduced by an output current of the feedback network (IFB,AC).
16. The circuit of claim 15, wherein the feedback network includes switches coupled between an input and output of the floating class AB output stage.
17. The circuit of claim 16, wherein, in response to an absolute value of an output of the floating class AB output stage exceeding twice a threshold voltage of level shift switches of the feedback network, the feedback network is configured to transition from capacitive operation to resistive operation based on a resistive channel of the switches controlled by the level shift switches.
18. That circuit of claim 15, wherein the preamplifier includes a bias voltage regulation loop that sets an input bias voltage for the floating class AB output stage.
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November 27, 2019
January 10, 2023
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